Ender 3 S1 ABL issue

  • Hi,
    I have been scratching my head at this for a while and can't figure it out.
    The probe seems to think that my bed is 0.2mm lower at the front than at the back, and that is after manually adjusting the 4 corner knobs with the paper method. I also double checked the gantry to bed distance at all 4 corners with a caliper to be sure that the bed is flat to the nozzle.
    Left to right seems OK though.

    I have checked that everything is square, all rollers and belts are just tight enough not too tight not too loose. I'm out of idea, I can't see a scenario where the delta z between the nozzle and the probe would be different depending if the bed is forward or backward when the bed to nozzle distance stay constant.
    Any suggestions?


  • @Armbrust Yeah I am starting to think its the probe. Not only do I get varying values, its every probe, because I can do a manual bed level, and z-offset, do a print and its excellent and I can visually see doing a large one layer print where the imperfections are with the physical bed as far as flatness is concerned, and that is ok, can manage manually getting that first layer a hair thicker to compensate. After that the layers are fine, but once you introduce ABL and let it probe, it completely changes it. Testing it was easy, manually level the bed, do z-offset. Then run ABL and go back to manual level and everything is completely off, and if you look at the map it creates, its off effectively based on that map so if left corner is high, after bed leveling is good and running ABL when you go back to that corner using bed level, its too tight. That is because ABL is adjusting Z levels dynamically to follow that faulty mesh created. If I run ABL again it is slightly different and the manual bed level is off again some other way.

    I think I will update to the BL touch and test it again. I was also kicking around replacing the bed entirely with a cast aluminum bed that would resolve the crappy cheap bed provided as well.

    The printer works for me, running Klipper, has a 7" touch screen, input shaper etc. But having to really dig deep to do bed leveling is a real pain. I did print all my voron 2.4r2 parts off it fine but I really know this printer now..

    As far as temperature, its not as large a factor as everyone thinks, I have done all leveling both ways and the deviation is not that much, unless you have some really tweaked bed, or extrusions that are fd up which only shows itself when enclosed like when I did my ABS prints, but mine are fine no twisted extrusions.

    I would however suggest that everyone with a S1 or S1 pro completely remove your Y axis off the printer, and put it back on, then only tighten it just over snug, do not wrench on it tight, then put the bed back on and redo the springs and relevel it. You will find your mesh improves greatly...

  • I have the same problem, when I manually level the bed, then do z-offset and save the config, then I run ABL for the bed mesh, the ABL mesh says the bed is correct at the front x&y corner but then the bed suddenly is off by well over 1mm opposite from that corner so the bed in the map image has one blue corner followed by a total red triangle for the rest. After running ABL if you run bed leveling either auto by macro or by hand it does not matter which, now the left front screw it tight, and the remaining other 3 corners the paper no longer touches the nozzle even though just a minute prior I finished doing it by hand and it was perfect.

    There is a bad side affect to the ABL now compensating for the strangeness, that is the nozzle now drags across infill lines. Which it never did the first week I got the system. FYI I measured the gantry to see if its level to the bed, and all three corners that are reported high are all equal distance to the gantry. The right front corner is off a hair just under 1mm and I believe that is caused by the silly screw hole were the bed is secured I think the bed dips a hair there. I know the gantry and z steppers/lead screws are aligned as I measured that and already corrected a nearly 3mm difference between the left and right sides. That is now equal as it should be and synchronized as it should be. Everything is tight, all rollers are spot on tightness wise etc. The only thing I can think of is the hot end may have some sort of give or something. I am going to play with its mount and see if I can get it to change with some adjustments.

    I think Armbrust may be someone correct in that the crtouch may be the culprit. However I am not sure how to clear the ABL data to correct this as of now as its already saved. In my case I am running Klipper and no longer running Marlin. But it was the same thing when it was stock.

    The printer as it sits is still attempting to compensate as far as I can tell, if I can zero out or disable ABL all together maybe it will work. I think swapping out the bed probe may not actually do much other than change the prob accuracy as a whole, which may not change what is off it may just show it is less off. I do not have one on hand to swap out to test right now but I may look into that later.

  • A factor that I believe is very important is bed temperature. Temperature will change the shape of the bed and it should be leveled either manually or automatically at the temperature you will be printing at. This is why it is important the the ABL function works. It maps the shape of the bed surface using 16 different points instead of just 4 as we do when we manually level the bed.

    Unfortunately I do not believe the ABL works right in the Ender 3 S1 Pro. It seems to produce somewhat random results. I noticed that it will only uses .05 mm increments when we adjust Z and I suspect it is using the same accuracy when we use ABL. That is almost 2/1000 of an inch, which to me seems to be too large of an increment. 0.05mm is 1/4 of the standard layer height of 0.20, that seems like way too much.

    BLTouch, which is similar to what Creality is using in the Ender 3 S1 Pro, advertises an accuracy of 0.01mm. That is five times more accurate than what the Ender firmware allows or about 1/20 of the layer height. That sounds more like it.

    I believe the correct procedure to level the bed is to first manually level it and if you do it properly you will get it more accurately than 0.05mm, then use ABL. I am guessing that you are now loosing some accuracy if it is 0.05mm increments. It becomes a bit of a trade of as it is now over 16 points instead of only 4.
    I would imagine that the 0.05 mm is a software or firmware setting and it is simply just set wrong!

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